Title : Reactive Oxygen Species (ROS) Act as Chemical Switch from Supporting Survival to Death of Cancer Cells
Reactive oxygen species (ROS) are a group of highly reactive oxygen centred free radical chemical species in normal and cancer cells. In normal cells, ROS are maintained in tight control of level of the antioxidants. On the other hand, the level of ROS is generally elevated in cancer cells, due partly to metabolic activities and cell divisions, which are believed to play a critical role in the process of tumorigenesis and cancer progression. It is further known that ROS can act as cancer suppressors depending on the varying antioxidant capacities of different types of cancers. These results suggest existence of a complex redox state in cancer cells, and they are regarded as intracellularly stressed. In this talk, I will discuss the mechanisms of involvement of ROS and their functions in the initiation, signaling and proliferation of cancer cells. It is pointed out that the delicate balance of ROS and antioxidants levels determine their role in survival and death processes of cancer cells. This redox situation offers novel anticancer therapy strategies to achieve the goal of greater cancer cell killing by increasing the ROS level in response to anticancer therapies such as chemotherapy and radiotherapy. It is concluded that ROS acts as a chemical switch from favouring survival to destruction of cancer cells improving radiotherapy in clinic.